Collapsible viewing instruments are easily produced out of simple materials. They are lightweight and fold into a flat shape. These relatively compact products provide their users with the advantages of portability and low cost. Typical collapsible viewers have fold lines which divide the original card into several distinct surfaces; they usually have holes and tabs and sometimes also need an adhesive such as tape or glue. This structure of the collapsible viewers can cause some problems. For the user, assembly may be difficult. This design also may lack the sturdiness required for outdoor use in a rigorous setting. Indeed, some of these viewers are constructed as disposable viewing tools which are disposed of after a single use. Problems can also arise regarding the optical properties of the collapsible viewers: when configured for storage, a surface is folded above a lens, or a lens is folded directly above a second lens, thus, instead of protecting the lens, it may actually abrade or scratch the lens. In addition, these viewing instruments in which the distance between the ocular and the objective lens is short may not provide as much magnification. In the case of binocular construction, universality of utility can be hampered by the fact that not all user's eyes are spaced apart precisely the same distance between the dual ocular lenses.
Collapsible viewers generally have three different configurations: a viewing configuration in which the collapsible viewer is a three dimensional object, a storage configuration, and the manufacturing blank configuration. The manufacturing blank is a single thin layer, both long and wide. The manufacturing blank then undergoes assembly by gluing, folding, engaging flanges, etc., and then can assume either a storage or a viewing configuration. When configured for storage the viewer is relatively flat, but it still consists of several layers making it quite thick and relatively cumbersome. As a result, although collapsible viewers are lightweight and relatively compact they are still carried as a separate item in a bag or in the pocket. The current invention tries to improve several properties of the collapsible viewer, in particular compactness. This will make the instrument very easy to carry, not as a separate item but just like adding another credit card to the wallet.
Attempts have been made to provide collapsible viewing instruments. For example, U.S. Pat. No. 4,239,328, issued Dec. 16, 1980 to H. L. Justice, Sr., et al. shows a collapsible binocular and blank therefor comprising a semi-rigid sheet material which is foldable into a housing having dual objective and ocular lenses. A flap system depending from a roughly rectangular foldable panel is used to secure the sides of the housing. U.S. Pat. No. 4,964,709, issued Oct. 23, 1990 to Hoeptner, U.S. Pat. No. 4,773,747, issued Sep. 27, 1988 to W. M. Bresnahan and U.S. Pat. No. 4,486,079, issued Dec. 4, 1984 to K. Ueda each teach a binocular system in which the housing is secured by flaps depending from a rectangular panel. U.S. Pat. No. 4,846,553, issued Jul. 11, 1989 to R. Rice discloses another binocular viewer which is assembled from a blank having walls that cooperate to form a bellows-like structure which may be secured with tabs and adhesive tape.
U.S. Pat. No. 5,528,419, issued Jun. 18, 1996 to R. C. Murrey teaches a flat-format binocular kit comprising a corrugated blank from which elements are removed for assembly. The assembled binocular may be worn by the user in a fashion resembling eyewear.
U.S. Pat. No. 4,881,334, issued Nov. 21, 1989 to M. Brown and U.S. Pat. No. 3,756,699, issued Sep. 4, 1973 to R. L. Martin show collapsible monocular viewers. Brown demonstrates a single lens viewer assembled from a unitary blank which is folded upon itself to form a housing, the internal sides of which are magnified when viewed through the single lens. When this viewer is configured for storage and is folded into two, its length and width are those of a credit card. Martin presents a mailable disposable viewer in which the manufacturing blank provides a mailing envelope. The viewer is formed from a section of the blank which is folded upon itself so that a depending tab may be inserted into an integral slit.
U.S. Pat. No. 4,968,125, issued Nov. 6, 1990 to V. Rodriquez shows a magnifier having both an ocular lens and a "condenser" mounted in register at opposing ends of a collapsible rectangular housing. The device is presented as a "charm" which may be hung from a keychain or the like.
U.S. Pat. Des. No. 349,295, issued Aug. 2, 1994 to P. Weidemann and U.S. Pat. Des. No. 240,333, issued Jun. 22, 1976 to M. G. Chesnut show monocular devices having ocular and objective lenses mounted to opposing ends of rectangular housings which appear to be rigid structures.
Despite the teachings of the prior art, a need still exists for a sturdy, easily assembled, collapsible viewing instrument which may be used repeatedly in divers settings. Additionally, it would be desirable to provide a collapsible viewing instrument that may be carried conveniently in a person's wallet, pocketbook or other personal object holder.